FIG. 3.
Effect of the presence of sotA and sotB on the induction of the lac and ara promoter in E. coli by various compounds. Strains P4X (induction by IPTG, lactose, or melibiose) containing plasmid pBR322 (□), pBRS1 (sotA) (◊), or pBRS6 (sotB) (○), or NM522/pBADuid (induction by arabinose) carrying plasmid pSU9 (□), pS1A (sotA) (◊), or pS6E (sotB) (○) were grown in LB medium to an optical density at 600 nm of 0.5. Inducer was added at the concentration indicated, and the β-galactosidase (β-gal) or β-glucuronidase (β-glu) activity of the culture was measured over time. (A) IPTG (4 × 10−5 M). (B) IPTG (3 × 10−6 M). (C) Lactose (20 mg/liter). (D) Lactose (5 mg/liter). (E) Melibiose (40 mg/liter). (F) Arabinose (4 mg/liter).